The studies reported here are part of a program to identify properties of rhinoviruses which might be used to place rhinovirus serotypes into groups with shared immunologic determinants and biologic functions. Antisera from guinea pigs immunized against individual human rhinovirus (HRV) serotypes previously used to determine cross-reactivity in an immunoblot system with the capsid surface peptides (VP1, VP2, VP3) of HRV serotypes 2 and 14 (HRV2 and HRV14)) were studied for similar reactivity in an enzyme immunoassay (EIA). For the EIA rhinoviruses were purified by CsCl gradient and attache to 96 well plates using carbonate buffer in a standard method. Dilutions of antisera from the immunized guinea pigs were reacted with the treated plates, and the binding of antibodies specific for rhinovirus antigens was identified by anti-guinea pig sera conjugated with alkaline phosphatase. Th preliminary results of the EIA paralleled the results previously found in immunoblots. Antisera specific for HRV2, HRV1B, and HRV89 which reacted strongly with HRV2 in immunoblot also reacted strongly with HRV2 in EIA. Antisera specific for HRV31 which was unreactive with HRV2 in immunoblot wa also unreactive with HRV2 in EIA. Antisera specific for other serotypes which reacted weakly with HRV2 in immunoblot were intermediate in reactivit in EIA. The pattern of reactivity was consistent with the correlation of immunoblot results and defined spectrum of susceptibility of the HRV serotypes to antiviral chemicals which bind to a relatively conserved amino acid sequence occupying a fold in the capsid surface of VP1. The data are consistent with conservation of immunogenic antigenic determinants.